Palash Sarkar

We introduce the idea of pushdown automata with the ability to flip

its stack. By bounding the number of times the stack can be flipped

we obtain a hierarchy of language classes from the context free

languages to the recursively enumerable languages. We show that each

class in ...
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Christoph Behle, Andreas Krebs, Stephanie Reifferscheid

Based on different concepts to obtain a finer notion of language recognition via finite monoids we develop an algebraic structure called typed monoid.

This leads to an algebraic description of regular and non regular languages.

We obtain for each language a unique minimal recognizing typed monoid, the typed syntactic monoid.

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